A cat at the bar I work at had a litter of kittens, we took 2 of them who have/had NO TAIL. Not even a bob, just no tail, born that way. One of the kittens had to be put down due to Feline infectious peritonitis. The other one (she is about 3 months old) who is a female is having issues. When she falls asleep or trys to clean herself she pees. She trys to use the litter box, but nothing ever comes out. We spend a considerable amount of time massaging her belly to help her poop. We have taken her to the vet several times and they haven't done anything to help. (Just lost my cat carrier and 2 of my towels). When she gets really stopped up beyond our help I have been giving her a half of a half of an exlax with her wet food. We're at a loss at this point. The vet said it might get better with age, it might not get better. Is there any tips or tricks that anyone can help me with?

HI!
I have two of those. First, find a different vet, jeez that ones sounds awful. They shoudl at least be willing to look up stuff and learn to help you.
I haven't used ex-lax, not sure how it is for cats.

Mira lax, maybe about a quarter teaspoon for a kitten, twice daily should help a lot. There are pet-safe enema, but do NOT give a human enema, if she hasn't pooped for 3 days. Giving SQ fluids is also very helpful, and your vet should have thought of that.

I would call around to different vet offices in your area, explain that you have these kittens and are unhappy with your current vet, you need someone who is willing to help them with constipation and incontinence problems.
Owners of special needs pets often have to stand up for their pets, it's kind of sad but it's true.

you can try expressing her bladder, sometimes when they are constipated that also makes it difficult for them to pee, not always but sometimes.

that is very very young for FIP. FIP generally occurs around 7 months old, also it is almost unheard of in outdoor cats. However, many vets who don't know what is going on will say 'FIP' rather than put time and effort into finding out what is going on. Get away from that vet, fast. I don't think she/he is committed to really helping a special needs kitten

I agree with Bendy. Not every vet is willing or able to deal with handicappers, and I wouldn't think that spina bifida would be such a foreign concept. I also agree about changing the laxative. I'm NO vet, but I've never heard that Ex-Lax is safe for critters.